Ecology fuel return systems

Abstract

A shut-off valve includes a float and a negative G control component. The float is configured to occlude a tank outlet at a first fluid level and 1 G and unocclude the tank outlet at a second fluid level and 1 G. The negative G control component is operatively connected to the float to limit fluid, e.g. liquid or gas, communication between a tank outlet and an ejector pump during negative G events. An ecology fuel return system includes a tank, an ejector pump, a float, and a negative G control component, as described above. The tank has an inlet and an outlet. The inlet is configured to be in fluid communication with components of an engine. The ejector pump is in fluid communication with the tank outlet and is configured to pump fuel from the tank to a fuel pump inlet of an engine.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to fuel return systems, and, in particular, to valves in fuel return systems.[0003]2. Description of Related Art[0004]Traditional ecology fuel return systems can be found in gas turbine engines, for example, in gas turbine engines used in aircraft. A traditional ecology fuel return system is generally configured to remove a certain known amount of jet fuel from the engine's fuel manifolds, for example, fuel nozzle / injector manifolds, engine fuel supply lines, and the like, upon engine shutdown. Upon engine startup, the jet fuel from the ecology fuel return system is returned to the engine's fuel pump inlet via an ejector pump to be injected in the combustor thus providing stable engine idle operations. Ecology fuel return systems can minimize the amount of fuel left over in the engine's fuel system after engine shutdown, thus minimizing the possibility for any liquid fuel and / or any gaseous...

AI Technical Summary

Benefits of technology

[0007]A shut-off valve includes a float and a negative G control component. The float is configured to occlude a tank outlet at a first fluid level and 1 G and unocclude the tank outlet at a second fluid level and 1 G. The negative G control component is operatively connected to the float to limit fluid communication between a tank outlet and an ejector pump during negative G events.

Problems solved by technology

Finally, ecology fuel return systems can drain the combustor of any unused fuel upon engine shut-down thus preventing any smoke exhaust from the engine upon engine start-up and potentially causing some localized undesirable fuel-rich conditions in the combustor (i.e., “hot spots”).

Traditional ecology fuel return systems can sometimes experience instability.

For example, there is a potential for air leakage into the aircraft's fuel system under some circumstances, such as negative G events that can occur during some flight maneuvers.

The air entrained in the fuel could interfere with normal operation of the engines.

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